This invention relates to the field of display systems, more particularly to display systems using spatial light modulators.
Spatial light modulators such as micromirror arrays and liquid crystal on silicon panels are used in many modern display applications. These modulators have found application in displays ranging from ultraportable projectors weighing less than three pounds, to theater grade projectors capable of performance exceeding that of existing film technologies.
In spite of the greatly varying performance of the projectors, the modulator used in all of the applications is very similar. The commonality of the modulators is a boon to the manufacturing process, but can have negative unintended consequences when the modulators are pin for pin compatible. This is particularly true when the modulators are especially screened or selected for use with particular display system. For example, if a modulator has excellent uniformity across the modulator array, it may be selected for use in a cinema application in which image quality is the all important criteria. Modulators with lesser performance may fail this screen and be allocated to display systems with less strict image quality requirements.
If a display manufacturer or end user were to replace the modulator of a cinema grade projector with the modulator that failed the image screening tests required of a cinema grade projector, the performance of the display system would be degraded. This could damage the reputation of the display manufacturer as well as the manufacturer of the modulator and, depending on the intensity levels the modulator is exposed to, damage the modulator. Therefore, there is a need for the modulator manufacturer to control the use of the spatial light modulators in order to prevent the modulators from being used in projectors they are not designed for.
Objects and advantages will be obvious, and will in part appear hereinafter and will be accomplished by the present invention which provides a method and system for limiting the operation of a spatial light modulator to a particular class of display systems. One embodiment of the claimed invention provides a method of operating a spatial light modulator, the method comprising: determining a peak level of light incident the modulator over a period of time; setting a threshold level equal to a fraction of the peak level; monitoring a current level of light incident the modulator; comparing the current level of light and the threshold level; and disabling the modulator based on the comparison.
Another embodiment of the disclosed invention provides a modulator array. The modulator comprises: a photosensitive circuit for outputting a light intensity signal representative of a level of light incident the photosensitive circuit; a threshold detection circuit 400 receiving the light intensity signal 402 and outputting an under threshold signal 408 indicative of whether the intensity signal is less than a threshold level; and a duty cycle detection circuit 410 for monitoring the under threshold signal 408 and outputting a disable signal 418 indicative of the duty cycle of the under threshold signal 408.